This invention relates to electronics assembly processes and apparatus in general, and more particularly to an improved vapor phase assembly process for high frequency stripline circuits.
Vapor phase soldering techniques have been developed recently for reflow soldering in electronics assembly, improving quality, yield, and at reduced cost. The general technique for vapor phase solder reflow is described in a paper delivered at the California Circuit Association, Oct. 21, 1975, by Donald J. Spigarelli and is further described in an article entitled "Condensation/Vapor-Phase Reflow Soldering" by Terrence Thompson, published June 1977, in "Assembly Engineering". That paper and publication provide useful background in the general application of the present invention and are hereby incorporated by reference thereto.
Although vapor phase techniques have found ready application in assembly structure utilizing solder as a joining element, and in circuit reflow applications eliminating solder bridges and icycles produced in a wave soldering process, the inherent advantages of condensation or vapor-phase solder heating techniques have not heretofore been fully realized in a process merely by placing an assembly in the vapor-phase zone of a soldering apparatus. The even heating aspect is limited by the functional access to the work piece provided by the production machinery, and further problems are encountered by the limitations of heat reserve contained in the vapor body, particularly when a large mass relative to the quantity of heat stored in the vapor is inserted into the vapor phase machine. The overall mass of the structure is a critical consideration in determining the length of time necessary for a complete reflow.